1. Field of the Invention
The present invention relates to an indicia printing/verifying apparatus having a self-verifying function, such as a bar code printer, and an indicia scanning method thereof.
2. Description of the Prior Art
As disclosed in U.S. Pat. No. 4,699,531, an indicia printing/verifying apparatus has been available, which is designed to print indicia, such as bar code, on a sheet of paper by using a print head, e.g., a thermal head, and to subsequently read the indicia using a scanner so as to verify the print result of the indicia.
In order to prevent a decrease in printing speed, this apparatus is designed to scan printed indicia by moving the scanner in a direction perpendicular to the line feed direction while performing line feed.
In such a conventional indicia scanning method, however, when the line feed speed (printing speed) is represented by v; the scanning time of the scanner, t; and the length of an indicia to be scanned in the line feed direction, l, the entire indicia cannot be scanned unless the relation indicated below is satisfied: EQU l.gtoreq.v.times.t (1)
According to this method, therefore, as the line feed speed (printing speed) v is increased, the scanning time t must be shortened. In order to shorten the scanning time t, a carriage drive motor for moving the scanner is required to have a large output. However, when a drive motor having a large output is used, the cost is increased, and the power consumption is greatly increased because of the motor.
If scanning is performed without performing line feed, since relation (1) need not be satisfied, the length l of indicia in the line feed direction can be increased. However, if the apparatus is designed in this manner, its printing/verifying speed (throughput) is decreased.